The virus

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Size & Content

Diameter: ≈100 nm

Volume: ~106 nm3 = 10-3 fL

Mass: ~103 MDa ≈ 1 fg


Spike trimer: Length ~10nm, copies per virion: ≈100

Nucleoprotein: ≈1000 copies (measured for SARS-CoV-1 )

Membrane protein: ≈2000 copies (measured for SARS-CoV-1 )

Envelope protein: ≈20 copies (100 monomeres, measured for TGEV coronavirus )


Replication timescales

in tissue-culture

Virion entry into cell: ~10 minutes (measured for SARS-CoV-1)

Eclipse period : ~10 hours

Burst size : ~103 viriouns (measured for MHV coronavirus )

Genome

The virus in the body



Evolution rate: ~10-3 nt-1 yr-1 (measured for SARS-CoV-1 )

Mutation rate: ~10-6 nt-1 cycle-1 (measured for MHV coronavirus )


Concentration

maximal observed values following diagnosis
(Woelfel et al. 2020; Kim et al. 2020; Pan et al. 2020;)


Nasopharynx : 106 - 109 RNAs/swab

Throat: 104 - 108 RNAs/swab

Stool: 104 - 108 RNAs/g

Sputum: 106 - 1011 RNAs/mL

RNA counts can markedly overestimate infectious virions


Host cells

(tentative list; number of cells per person)
Type I & II pneumocytes (~1011 cells)
Alveolar macrophage (~1010 cells)
Mucous cell in nasal cavity (~109 cells)
Host cell volume: ~103 µm3 = 103 fL

Epidemiology


"Characteristic" Infection Progression in a Single Patient

Basic reproductive number R0: typically 2-4
Varies further across space and time (Li et al 2020; Park et al. 2020)


Inter-individual variability is substantial and not well characterized. The estimates are parameter fits for population median in China and do not describe this variability (Li et al. 2020; He et al. 2020).


Incubation period: ≈5 days
(99% < 14 days unless asymptomatic)

Latend period: ≈3 days

Case Fatality Rate: ≈0.8%-10%

Infected Fatality Rate: ≈0.3%-1.3%


Antibody Response - Seroconversion

Antibodies appear in blood after: ≈10-20 days

Maintenance of antibody response: ≈2-3 years (measured for SARS-CoV-1 )


Virus Environmental Stability

Half-life Time to decay 1000-fold
Aerosols ≈1 hr ≈4-24 hr
Surfaces ≈1-7 hr ≈4-96 hr

Based on quantifying infectious virions. Tested at 21-23°C and 40-65% relative humidity. Numbers will vary between conditions and surface types (Otter et al. 2016). Viral RNA observed on surfaces after a few weeks (Moriarty et al. 2020)